The present invention relates to an environmental control apparatus and, more particularly, it relates to an environmental control apparatus to be mounted in a device fabrication apparatus which requires a clean environment in producing such plate-like devices as semiconductor and liquid-crystal devices.
Since the fabrication processes for semiconductor, liquid-crystal, or like devices require a clean environment, it is necessary that an apparatus for producing these devices is placed in a clean environment. Hence, the device fabrication apparatus mentioned above is typically installed in such a clean room as shown in FIG. 15.
A variety of clean rooms are shown in pp.93-97 of "Clean Room Handbook" published by Japan Air Cleaning Association. Among them, the clean room shown in FIG. 15 is cited from FIG. 2.2.13 in p.96 of the same book. In FIG. 15, the device fabrication apparatus 51 is disposed in a clean area 52, for it requires a clean environment in producing plate-like devices.
The air blown into a ceiling area 54 by a blowing fan 53 is cleaned by a high-efficiency filter 55, so as to be supplied to the clean area 52. The air exhausted from the clean area 52 to an underfloor area 5B flows through a first duct 57, while a conditioned air introduced from outside flows through a second duct 58, both of which are blown into the ceiling area 54 by the blowing fan 53.
However, the provision of such a clean room in the aforesaid device fabrication system is disadvantageous in that the resulting system becomes larger in scale and hence requires a heavy investment. Moreover, a huge amount of maintenance cost is necessary in order to clean the entire clean room and to maintain a specified degree of cleanliness therein.
In view of the foregoing, there has recently been proposed an environmental control apparatus to be mounted in a device fabrication apparatus which requires a clean environment in producing devices, though the drawings thereof are omitted here.
The environmental control apparatus comprises an air-tight chamber containing a clean air, an entrance formed in the chamber through which devices are carried into the chamber, an exit formed in the chamber through which the devices are carried out of the chamber toward the device fabrication apparatus, and a means for conveying the devices in the chamber from the entrance to the exit.
As smaller device features are defined in such devices as semiconductor and liquid-crystal devices, a higher degree of cleanliness has been required in the environment in which the device fabrication apparatus for producing these devices is placed.
However, the conventional environmental control apparatus mentioned above is disadvantageous in that it requires a clean-air supplying device to supply a clean air into the chamber and that small impurities generated in the chamber are not removed.